Conventionally, various forms of indicia are provided on a sidewall of a tire. With respect to a given tire design, it may not be necessary or desirable to change certain indicia for the life of the mold. On the other hand, for indicia such as serial numbers or the like, it may be desirable or necessary to provide some means to be able to readily change such indicia with respect to groups of, or individual, tires.
A conventional tire mold may include a mold member having a surface which is engageable with a portion of a tire to form a surface on the tire during a tire vulcanizing or curing operation. The surface may form at least a portion of the exterior surface of a sidewall of a tire. The surface may be a surface of revolution having an axis corresponding to the axis of revolution of a tire cured in a mold.
An indicia forming member or coverplate may be attachable to the mold member. The coverplate may be provided with indicia forming means. Such indicia forming means may be projections extending from the coverplate or recesses in the coverplate depending on whether it is desirable to have the indicia which is formed on the tire to be recessed or raised.
A conventional mold member may be provided with a pair of keyhole slots spaced apart a predetermined distance angularly about the axis of revolution of the surface. The coverplate may be provided with a projection located adjacent each end thereof. Each projection may extend from the side of the coverplate opposite that which carries indicia forming elements. Each projection or keeper may have a cylindrical portion fixed at one end to the coverplate and extending from the coverplate at right angles to the general plane thereof. The outer end of each portion may terminate in an enlarged portion. The diameter and configuration of each enlarged portion may be such that it will fit freely within the enlarged portion of one of the keyhole slots in the mold member. The diameter of the portion of each projection may be selected so that the portion is slidably receivable within the narrower portion of a keyhole slot. The keyhole slots may be oriented in the mold member and spaced apart a distance corresponding to the spacing of the projections on the coverplate such that, when the coverplate is moved toward the mold member, the projections may enter and be received in the enlarged portions of these slots. Thereafter, translation of the coverplate in one direction will move the cylindrical portions of the projections into the narrower portions of the slots so that coverplate is retained on the mold member.
In order to provide selective retention of a coverplate on a mold, a conventional latch mechanism may be provided. The latch mechanism has comprised a body portion receivable within a recess or opening in the mold. The recess has been disposed approximately midway between keyhole slots. The latch mechanism has further comprised a plate seated on top of the body and releasably secured thereto by a pair of screws. The plate closes the recess in the mold in which the body of the latch mechanism is received, except for a keyhole slot in the plate similar to the above described keyhole slots and oriented in the same manner as those keyhole slots. Thus, the narrower portion of the slot extends from the enlarged portion thereof in the same direction along the line as the narrower portions of the slots extend from the enlarged portions thereof.
The conventional latch mechanism has been provided with a recess, which in conjunction with the plate, provides a chamber within the body. Slidably received within the chamber are cam means in the form of a slide mounted for movement in a direction in alignment with the narrow portion of the keyhole slot in the plate. The conventional slide is movable between a retracted position and a latching position. The slide is retained in its retracted position by a spring loaded detent which extends coaxially of the enlarged portion of the keyhole slot and is received within an opening in the body of the latch mechanism. The spring for the detent is received within the same opening as the detent. The end of the opening, which receives the detent and spring, is closed at the end thereof opposite the detent by set screws, which also serve to preload the spring to urge the detent toward the chamber.
The conventional slide is maintained in its retracted position by the detent, one end of which is urged into the recess and into obstructing relation with the slide to prevent movement of the slide in a direction toward the narrower portion of the keyhole slot. A preloaded spring is engaged between the end of the slide opposite the detent and a wall of the chamber and urges the slide in a direction toward the narrower portion of the keyhole slot. The free length of the spring is such that when the slide is in its latching position, the spring will still preload the slide sufficiently for a purpose to be later described.
A conventional projection or keeper is carried by the coverplate. The keeper extends from the side of the coverplate opposite the indicia forming portion of the insert and is positioned between the projections such that when the enlarged ends of the projections are positioned in registry with the enlarged portions of the keyhole slots, the keeper will be in registry with the enlarged portion of the keyhole slot in the top plate of the latch mechanism. The keeper extends from the coverplate at right angles to the general plane thereof and has a generally cylindrical cross-section. The keeper at the end thereof adjacent the coverplate is cutaway, or formed, to provide parallel surfaces. When the coverplate is located such that the projections are in registry with the enlarged portions of their respectively associated keyhole slots, the surfaces will be parallel to the sidewalls of the narrower portion of the keyhole slot. Additionally, the surfaces are spaced apart a distance only slightly less than the spacing of the sidewalls of the narrow portion of the slot. Thus, it will be seen that the forming of the surfaces on the projections provides a pair of slots formed in part by the projections and in part by the coverplate, with such slots being adapted to slidably receive the bordering edge portions of the narrower portion of the slot. The projection is further provided at the end thereof opposite the spring with an inclined cam surface which lies in a plane extending at right angles to the planes of the surfaces. The surface cooperates with a similarly inclined surface provided by the end of the slide opposite the spring.
To mount the conventional coverplate on the mold, the coverplate is positioned with the enlarged portions of the projections disposed in the enlarged openings of their respectively associated keyhole slots. The center portion of the coverplate is then pressed toward the mold whereby the distal end of the projection will engage the detent so that in response to further movement of the coverplate toward the mold, the detent will be depressed sufficiently against the force of the spring to permit the spring to move the slide in a direction toward the narrower portion of the slot. This movement of the slide moves the projection into the narrower portion of the slot whereby the coverplate will be captured and retained on the mold by the interrelationship of the slots formed by the coverplate and projection and the bordering edge portions of the narrow portion of the slot. The force of the spring maintains the projection engaged with the closed end of the narrower portion of the slot. Concommittantly with the movement of the projection into the narrow end of the keyhole slot, the projections will be moved into the narrower ends of the slots, whereby the end portions of the coverplate will be retained on the mold.
To disengage the conventional coverplate from the mold, the coverplate is moved manually in a direction to move the projection into registry with the enlarged portion of the slot and against the force of the spring. Upon sufficient movement of the coverplate in this direction, the detent is urged outwardly into the chamber and into obstructing relationship with the slide to retain the slide in its retracted position. As the coverplate is moved in a direction to release it from the mold, the inclined surfaces on the slide and projection, respectively, act as camming surfaces to move the projection and thus the coverplate in a direction away from the surface of the mold.
It would be desirable to provide a more efficient and faster method and apparatus for interchanging indicia of tire molds.
One conventional impact device may use compressed air for suddenly pushing a piston within the impact device. The pushed piston drives a striking pin to drive an impact head portion that is arranged in a front end of the conventional impact device. The conventional impact device may comprise a main body having a cavity defined for receiving a spring and a sleeve that has an annular groove defined in an outer periphery of the sleeve. A passage may be defined in the main body and may selectively communicate with the annular groove for allowing compressed air flow into the sleeve. A block and a cylinder may be sequentially received in the cavity. A striker may be reciprocally and movably received in the cylinder due to the block and the compressed air. A shaft may extend longitudinally into the cylinder and the striker may be moved to impact the shaft for driving an impact head portion when the shaft and the cylinder are backward pushed to make the annular groove communicate with the passage to guide the compressed air flowing to the cylinder for pushing the impact head portion. Another conventional impact device may use electrical power for suddenly driving an impact head portion similar to the compressed air device.